Nozzle control for turbines.



W. J. IRWIN.

NOZZLE CONTROL FOR TURBINES.

APPLICATION FILED .AUG. l 7, 19M.

M 59, Patented Jan. 22, 1918. 2 SHEETS-SHEET1.

' FIEJL WITNESSES APPLICATION FILED AUG-17,1914.

Patented J an. 22, 1918.

2 SHEETS-SHEET 2.

WITNLESQES WILLIAM J. IRWIN, 0F WILKINSBURG, PENNSYLVANIA.

NOZZLE CONTROL FOR TURBINES.

Specification of Letters Patent.

Patented Jan.22, 191%.

Application filed August 17, 1914. Serial No. 857,031.

To all whom it may concern Be it known that 1, WILLIAM J. IRWIN, a subject of the King of Great Britain, residing at VVilkinsburg, in the county of Allegheny and State of Pennsylvania, have invented certain new and useful Improvements in Nozzle Controls for Turbines, of which the following is a specification.

This invention relates to that class of turbines used for converting any expansible fluid under pressure into useful work.

The object of this invention is to prevent loss of efliciency by throttling the steam or other gaseous fluid and at the same time to limit the fiow of steam to that required under the following conditions, viz z when the turbine is running at light loads; when the back pressure or vacuum is changed; when the initial pressure for operating the turbine is changed. It is also proposed to give an approximate proper expansion ratio of exit to throat area of the nozzle for the following conditions, viz:-when there is a decrease in the pressure at the exit of nozzle of a multi-stage turbine operating at partial loads; when the back pressure or vacuum is changed in the turbine; when the initial pressure at which the turbine is operating is changed; and when back pressureor vacuum as well as initial pressure is changed at the same time.

Attempts have been made prior to my invention to accomplish the above objects, but these have been objectionable for the following reasons: In order to obtain a correct expansion ratio of the motive fluid irrespective of the pressure at which the motive fluid passes through the nozzle, the nozzles have heretofore been constructed with collapsible walls so as to reduce the throat area of the nozzle for fluid at lower initial pressure to give the proper rate of steam flow for the load, at the same time attempting to give the proper exit area for the conditions under which the nozzle is working. Such nozzles have been objectionable for the reason that the nozzles were primarily set at. the proper angle of inclination with respect to the blades of the rotor. any movement imparted to the walls of the nozzle had a tendency to destroy the proper angle of inclination of the nozzle to the blades, or, in some cases, where this was not true, the mechanism employed was such that a plurality of nozzles could not be intimately grouped together, and as a result, prohibitive distances existed between individual nozzles and the uniting of the separate streams of motive fluid into practically one stream on to the blades could not be accomplished. Previous devices have also been unsuitable for reentrant turbines, because the walls of reversing chamber following the nozzle would not be in their proper positions for all loads, while with the invention herein described, the position of the walls of the reversing chamber can be fixed in such position as to be practically correct for all working conditions.

According to my invention, I am enabled to provide means whereby throttling losses are eliminated, the rate of flow is regulated and approximately the proper angle and approximately the proper expansion ratio of the nozzle is obtained, by varying the throat area and the relation of throat to exit area thereof to provide for fractional loads as well as for full load, or to suit the change of operating conditions. I am enabled to accomplish this without disturbing nozzle walls and still have approximately the proper inclination of the nozzles, because the nozzle angle changes very little when working with high velocities for fractional loads. This also permits a close grouping of the nozzles in the steam chest.

My invention also contemplates the provision of means for directing the motive fluid through the nozzle in substantially parallel stream lines so that eddy currents usually present where puppet valves are employed will'be eliminated when the alve is partially opened.

In the drawings, Figure 1 is a sectional view through a steam chest of a turbine onstructed in accordance with my invention.

Fig. 2 is a detailed perspective view of one shown in Fig. 2 as consisting substantially In the construction shown in Fig. 1, 1O designates a steam. chest provided with a nozzle 11 of usual construction and inclined With relation to the blades 12 and 13 and the vanes 14 of the rotor 15. on the shaft 16. 17 is a valve of which there may be one for each nozzle. One form of the valve is best vary the port or throat area of the nozzle so as to vary the amount of steam passed and also the expansion ratio of the nozzle to suit different pressures at the nozzle exit.

Various Ways, either by automatic or hand control, may be provided for operating the valve or valves 17, but one effective way is through the medium of a relay here shown as consisting of a cylinder 20, a pisten 21' therein connected to the stem 19, a spring 22 bearing against one end of the piston 21 and a apted to be opposed by pressure in the. chamber 23 admitted through a port 24 adapted to be in communication with the motive fluid pipe 25 and adapted to be opened and closed by a valve 26 connectedto a link 27 and a floating lever 28 attached at one end to thepis ton stem 29 and at the other end to the rod 30 of the governor 31. 32 is an exhaust port for the chamber 23, the eflective port area of which may be controlled by a needle valve 33 ofany preferred form.

When the parts are properly assembled and the turbineis operating under heavy load, the governor will be operative to open the port 24 so that motive fluid may pass through the port 24 into the chamber 23 and impart movement to the piston 21 against the spring 22. Inasmuch as the stem 19 of the valve 17 is rigidly connected to the piston 21, the outward movement of the piston 21 will be effective in imparting an opening movement to the valve 17 so that more steam may'be'admittedto the nozzle 11. Should an overload exist on the turbine, the movement of the piston 21 may be such that the nozzle 11 may be entirely uncovered to admit the maximum amount of steam thereto. It is apparent that full load may be carried by the nozzle when the valve is entirely withdrawn therefrom.

In the event, however, that fractional load existson the turbine, the port 24 will be closed or partially closed so that the spring 22 opposing the pressure in chamber 23 will force a suliicient amount of fluid out through the port 32 to permit the valve 17 pet valves 34 and 35, said to extend farther into the nozzle 11 and thereby close off or reduce the effective port area of said nozzle 11, and at the same time so proportion the effective area of the nozzle that the proper expansion ratio, or at least a much better expansion ratio, and consequently a higher motor eflicieney will be provided, for the incoming motive fluid than would be possible with an ordinary throttle or puppet valve.

An additional advantage is that the gradually increasing cross sectional area of the valve in combination with the walls of the nozzle insures the motive fluid from pass ing from the steam chest through the nozzles in substantially parallel stream lines so that there will be practically no eddy currents which will be detrimental to the ellieiency of the motor, and there cannot be any steam leaks in the nozzle walls as in previous devices.

In Figs. 3 and 4, I have shown a slightly modified form of nozzle control in which there are a plurality of valves 17 in a plurality of nozzles 11, and each valve is connected to a common valve head 18 operated by a single stem 19.

In Fig. 4, the nozzle shown is such that it may remain uniform in area until within a short distance of the end and then will be gradually increased in area, if desired, thus minimizing velocity losses in, the nozzle. It is obvious that the nozzles having puppet valve endings or short projections in them (see Figs. 5-7) may be either curved or straight as desired. If so desired, the entrance portion of the nozzle under the puppet valve ends, or short projections, may be considerably larger than the throat and remain so until within ordinary nozzle length of the exit when it will contract to form a throat, and, if necessary, again expand. This gives lower velocity in the first part of the nozzle and reduces losses.

In Fig. 5, I have shown the valve 17 on a head 18 combined with spring pressed pup valves being provided with stems 36 and 37 on which are cellars 38 and 39 against which springs 40 and 41 press so that the valves 34 and 35 will be resiliently seated on the seats of their nozzles 42 and 43. With such a construction, the valves 34 and 35 will become seated just. prior to the seating of the head 18 which carries the valves 17. According to this construction, the valves may be so arranged that the wedges 17 are first opened to talre care of light loads and then, when a heavy load is imposed upon the nozzle, the puppet valve is opened. A reverse order may be provided if desired,

'In Fig. 6, I have shown the nozzles 1'! ol substantially uniform length and the valves 17 of substantially uniform length, the

valves 17 being connected to a common head 18 provided With a stem. 19. In this form the valves Will have the same curvature as their nozzles and as a result the motion oi: the stem 19 will be slightly spiral.

In F ig. 7, I have shown a plurality of intermediate nozzles 11 with nozzles 45 and lb, the nozzles 11 being closed by the valve 17 on the head 18 while the nozzles &5 and as may be closed by puppet valves 4-7 and 48 rigid on the head 18 which is also provided with a stem 19.

Where it is desired to carry overload on a turbine and yet to employ but a single valve, it may sometimes be necessary to make the end of the nozzle a little larger at the entrance than toward the intermediate portion thereof and then increase the size of the nozzle at the exit in order to give proper expansion ratio to suit conditions. According to such a construction, at full load the valve wedges remain partially Within the nozzle entrance, while for overload the wedges will be completely withdrawn so as not to in any manner effect the entrance of the motive fluid into the nozzles through which they pass into the turbine.

From the foregoing, it will be obvious that the disadvantages of having a sudden drop in pressure at the entrance of the nozzle due to throttling and theencountering of eddy currents in the operation of the turbine will be prevented by employing valve control in accordance with my invention. It will also be apparent that the nozzles and valves jointly will provide approximately proper expansion ratio of the steam or other expansive fluid at the particular pressure under which the turbine is operated. In other words, if the pressure at the nozzle entrance rei'nains the same and the pressure at the exit of the nozzle is decreased either by change of back pressure or vacuum, or by cl'ianging the load on a multi-pressure stage turbine, approximately the proper expansion ratio will be provided and only the necessary amount of steam will be passed, hence, throttling losses are eliminated. The above is also true if the initial pressure for operating the turbine is changed. Any of the above named de ices may be operated by hand control in aiding to produce economy at different loads and under different operating conditions. The motive fluid will also be guided in substantially parallel stream lines against the rotor blades.

hat I claim is 1. In a turbine, a plurality of .nozzles, a plurality of wedgeshaped valves extending within said nozzle, and a valve head to which said valves are rigidly connected, and resiliently supported puppet valves carried by said head.

2. In a turbine, a pluality of nozzles, a

plurality of valves extending Within said nozzles and having variable cross sectional areas, a head to which all of said valves are connected, and puppet valves carried by said head.

3. In a turbine, a plurality of nozzles, a plurality of elongated valves extending into said nozzles, and a common carrier adapted to actuate all of said valves.

4. In a turbine, a plurality of nozzles, elongated valves extending into some of said nozzles, and puppet valves for others of said nozzles, a common carrier for all. of said valves, and said puppet valves being adapted to'open after said elongated valves have opened an appreciable distance.

5. In a turbine, a plurality of nozzles, elongated valves extending into some 01 said nozzles, and puppet valves for others of said nozzles, a common carrier for all of said valves, and some of said valves being adapted to open after other of said valves have opened an appreciable distance.

6. In a turbine, a plurality of nozzles, an elongated valve extending into one of said nozzles, a puppet valve for one of said nozzles, and a carrier common to said valves.

7. In a turbine, a plurality of nozzles, a plurality of valves of variable cross-sectional area extending into said nozzles for an appreciable distance and a carrier common to all of said valves.

8. In a turbine, a plurality of nozzles having channels rectangular at exits, a plurality of valves each of variable cross-sectional area, extending into said nozzles for an appreciable distance, and a carrier common to all of said valves.

9. In a turbine, a plurality of nozzles, an elongated valve of variable cross-sectional area, extending into one of said nozzles, a puppet valvefor one of said nozzles and a carrier common to said'valves.

10. In a turbine, a plurality of nozzles having rectangular passages at exits, an elongated valve of variable cross-sectional area extending into one of said nozzles, a puppet valve for one of said nozzles, and a carrier common to said valves.

11. In a turbine, a plurality of nozzles, an elongated valve of variable cross-sectional area extending into one of said nozzles, and a carrier common to said valves, the elongated valve being held against relative lontudinal. movement with respect to said can rier, and the puppet valvebeing resiliently supported by said carrier.

7 12. In a turbine, a plurality of nozzles having. rectangular passages at exits, an

elongated valve of variable cross-sectional area extending into one of said nozzles, a puppet valve for one 01": said nozzles, and a carrier common to said valves, the elongated valve being held against relative longitucliiml movement With respect to said carrier, to said carrier so as to open at :1 later time and the puppet valve being resiliently supthan others of said valves. 16 ported by said carrier. In testimony whereof, I nflix my signature 13. In a turbine, a plurality of nozzles {L in presence of two Witnesses. plurality of valves for said nozzles, a com- WILLIAM J. TRVVIN.

7 men carrier for said valves and adapted to lVitnesses:

reciprocate the same, some of said valves G120. E. CURRY, having longltucllnal movement Wlth respect JOSEPH A. BELL.

Copies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents Washington, D. G. 

